A bus bar is a metal strip or bar that conducts electricity and is used for electrical power distribution. Battery cells can be connected with bus bars to make battery packs. Some battery packs using cylindrical cells make electrical connections to the tops and the bottoms of the cells. When connecting cells in series, bus bars and high current interconnects link the positive terminal of one cell, or a parallel group of cells, to the negative terminal of the next cell or the next parallel group of cells. Unfortunately, connections to the bottoms of the cells may prevent the efficient operation of either an air-based or a liquid coolant-based cooling system that is being used to remove the heat generated by the cells during operation. In addition, the high current interconnect from the bottoms of the cells to the bus bars, which may be in the form of a wire somewhat longer than the length of the cell, introduces a small amount of resistance which gives rise to a voltage drop at high current levels. Furthermore, assembly of this wire to the bus bars and/or to the bottom of each of the batteries adds to the manufacturing cost of the battery pack while potentially introducing reliability issues.
Accordingly, what is needed is a robust bus bar configuration that allows the efficient assembly of a battery pack system while not affecting operation of the battery pack thermal management system. The present invention provides such a bus bar design.